1. Field of the Invention
The present invention relates to a frame structure for housing printed-circuit boards to be assembled in electric and electronic devices, as well as panel plates for use in other industrial fields (e.g. panels used as construction materials). More particularly, the present invention relates to a frame structure that is capable of accommodating variations in the width dimensions of the panel plates to be housed.
2. Description of the Prior Art
A prior art frame structure that is capable of housing panel plates having varying widths is shown in FIG. 6. The frame structure consists of a top plate 1 that is spaced from a bottom plate 2 and fixed thereto by means of four support columns 41. The frame structure also has an immovable side frame board 4 that is erected on either the left or right side, and a movable side frame board 5 that is erected on the other side and which is movable in the horizontal direction.
The opposing inner faces of the two side frame boards 4 and 5 are provided with a plurality of horizontally extending lateral grooves and a panel plate P is supported by one lateral groove on the frame board 4 and a corresponding groove on the other frame board 5. In order to secure the movable side frame board 5 at a desired position, a pair of sliding frames 43 are arranged between the top plate 1 and the bottom plate 2. Each of the plates is provided with a pair of parallel slots 6 through which are respectively inserted the threaded portions of fastening members 42 such as hexagon headed bolt or thumbscrew, protruded upwardly and downwardly from the sliding frames, that can fasten said frames 43 by mating members 44 such as nut at the outside of the movable frame board 5. Sliding frames 43 are disposed outside the movable side frame board 5 at a position corresponding to the slot 6 in such a manner that each of the frames 43 is secured at its top and bottom by means of a combination of the fastening member 42 and a mating member 44 such as a nut.
By proper adjustment of the sliding frames 43, the side frame board 5 can be fixed at such a position that the distance between the two side frame boards becomes equal to the width of each of the panel plates P to be housed. It then becomes possible to slide the panel plates along opposing lateral grooves 10 and 10a on the two side frame boards and support them in position.
A problem with the prior art frame structure shown in FIG. 6 is that since the tendency of the movable side frame board 5 to deflect increases as the size of the frame structure increases, pushing or pulling a certain portion of the frame board 5 by hand is not sufficient to allow equal forces to act on the threaded portions of all the fastening members 42 in the slots 6. The four fastening members 42, two of them being on the top plate 1 and the other two on the bottom plate 2, will not move over equal distances and instead, a great resistance will work solely on the threaded portion of the fastening member 42 in a certain slot 6, thereby making it difficult for the side frame board 5 to move smoothly. Even if one can manage to move the frame board 5, the distance between two side frame boards 4 and 5 will sometimes vary at the top and bottom portions or at the front and rear portions. Such variations in the distance between the two side frame boards will cause problems in subsequent housing of panel plates and must be eliminated by a certain readjustment operation.